Young men with a higher level of cardiorespiratory fitness have a significantly lower risk of developing several cancers in later life, according to the findings of a new study published in the British Journal of Sports Medicine.
It is already known that aerobic exercise induces interleukin-6 and suppresses a marker of DNA damage, which may account for a protective role in colon cancer. But whether being fit could reduce the risk of developing cancer in later life is far less clear.
For the recent study, Swedish researchers set out to assess the associations between cardiorespiratory fitness in young men and the incidence of site-specific cancer.
They turned to data held on men who underwent military conscription between 1968 and 2005 and for whom cardiorespiratory function was assessed by maximal aerobic workload cycle test at conscription.
The men’s level of fitness was then categorised as low, moderate or high, and those who received a cancer diagnosis before or within five years after the military conscription were excluded from the analysis.
Cardiorespiratory fitness and cancer
The team included 1,078,000 men, of whom 6.9% subsequently developed cancer in at least one site during a mean follow-up of 33 years.
A higher cardiorespiratory fitness was linearly associated with a significantly lower risk of developing nine different cancers. This included cancer in the head and neck (Hazard ratio, HR = 0.81), oesophagus (HR = 0.61), stomach (HR = 0.79), pancreas (HR = 0.88) and liver (HR = 0.60).
In contrast, a higher cardiorespiratory fitness significantly increased the risk of being diagnosed with prostate cancer (HR = 1.07) and malignant skin cancer (HR = 1.31).
While it is an observational study and no firm conclusions can be drawn about cause and effect, the researchers suggested that the findings strengthened the incentive for promoting interventions aimed at increasing cardiorespiratory fitness in younger people.
